Labs / Geography
Build a River Delta
A muddy river slows as it meets the still sea and drops its load, piling up new land and splitting into branching distributary channels. Turn the sediment, wave, and tide dials — and drag the river mouth — to see which process wins and what shape the delta takes.
Area 0 km²Channels 1Driver RiverShape Birdsfoot
What to try
- Crank sediment high with waves and tide near zero. Why do the channels stretch into long, clawed “birdsfoot” fingers?
- Now push the wave slider up. What happens to those fingers, and why does the coastline round off into a smooth arc?
- Raise the tidal range instead. Why do the channels start running straight out to sea like the bars of an estuary?
- Watch the channel count as the delta grows. When does a single river mouth split into many, and what makes an old channel go quiet?
- Drag the river mouth to a new spot. Where does the sediment go now, and what happens to the delta you already built?